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AP Bio #1 Chapter 1: Themes in the Study of Life Chapter 2: Chemical Context of Life Chapter 3: Water and the Fitness of the Environment Chapter 4: Carbon Unifying Themes in Biology Evolution~ biology’s core theme; differential reproductive success Emergent Properties~ hierarchy of life The Cell~ all organism’s basic structure Heritable Information~ DNA Structure & Function~ form and function Environmental Interaction~ organisms are open systems Regulation~ feedback mechanisms Unity & Diversity~ universal genetic code Scientific Inquiry~ observation; testing; repeatability Science, Technology & Society~ functions of our world Chemical Context of Life Matter (space & mass) Element; compound The atom Atomic number (# of protons); mass number (protons + neutrons) Isotopes (different # of neutrons); radioactive isotopes (nuclear decay) Energy (ability to do work); energy levels (electron states of potential energy) Chemical Bonding Covalent Double covalent Nonpolar covalent Polar covalent Ionic Hydrogen van der Waals Covalent Bonding Sharing pair of valence electrons Number of electrons required to complete an atom’s valence shell determines how many bonds will form Ex: Hydrogen & oxygen bonding in water; methane Polar/nonpolar covalent bonds Electronegativity attraction for electrons Nonpolar covalent •electrons shared equally •Ex: diatomic H and O Polar covalent •one atom more electronegative than the other (charged) •Ex: water Polar/nonpolar bonds Ionic bonding High electronegativity difference strips valence electrons away from another atom Electron transfer creates ions (charged atoms) Cation (positive ion); anion (negative ion) Ex: Salts (sodium chloride) Hydrogen bonds Hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom (oxygen or nitrogen) van der Waals interactions Weak interactions between molecules or parts of molecules that are brought about by localized change fluctuations Due to the fact that electrons are constantly in motion and at any given instant, ever-changing “hot spots” of negative or positive charge may develop Water Polar~ opposite ends, opposite charges Cohesion~ H+ bonds holding molecules together Adhesion~ H+ bonds holding molecules to another substance Surface tension~ measurement of the difficulty to break or stretch the surface of a liquid Specific heat~ amount of heat absorbed or lost to change temperature by 1oC Heat of vaporization~ quantity of heat required to convert 1g from liquid to gas states Density………. Density Less dense as solid than liquid Due to hydrogen bonding Crystalline lattice keeps molecules at a distance Acid/Base & pH Dissociation of water into a hydrogen ion and a hydroxide ion Acid: increases the hydrogen concentration of a solution Base: reduces the hydrogen ion concentration of a solution pH: “power of hydrogen” Buffers: substances that minimize H+ and OHconcentrations (accepts or donates H+ ions) Organic chemistry • Biological thought: • Vitalism (life force outside physical & chemical laws) Berzelius • Mechanism (all natural phenomena are governed by physical & chemical laws) Miller • Carbon tetravalence tetrahedron shape determines function Hydrocarbons • Only carbon & hydrogen (petroleum; lipid ‘tails’) • Covalent bonding; nonpolar • High energy storage • Isomers (same molecular formula, but different structure & properties) • structural~differing covalent bonding arrangement • geometric~differing spatial arrangement • enantiomers~mirror images pharmacological industry (thalidomide) Functional Groups, I • Attachments that replace one or more of the hydrogens bonded to the carbon skeleton of the hydrocarbon • Each has a unique property from one organic to another • Hydroxyl Group H bonded to O; alcohols; polar (oxygen); solubility in water • Carbonyl Group C double bond to O; At end of H C : aldehyde Otherwise: ketone Functional Groups, II • Carboxyl Group O double bonded to C to hydroxyl; carboxylic acids; covalent bond between O and H; polar; dissociation, H ion • Sulfhydral Group sulfur bonded to H; thiols • Phosphate Group • Amino Group N to 2 H atoms; amines; acts as a base (+1) phosphate ion; covalently attached by 1 of its O to the C skeleton;